如何从html中获取选定值到asp.net中的控制器

Question

我在html中有一个选中的框，当我选择用户时，它可以正常工作，因为它从数据库中获取信息。但是，当我选择“否”时，它将无法工作，并且无法保存表格。我正在尝试在Controller中获得无人值守，但我不知道该怎么做。

HTML

     <span>Assign to</span> <br />
        <select class="feddCell-assign" style="width: 100%;">

            <option  value="0">No one</option>
            @foreach (User associate in ViewBag.MyPals)
            {
                <option value="@associate.Email_Address">@associate.FirstName @associate.LastName</option>

            }
        </select> <br />
        <div class="personList"></div><br />

        <input type="button" value="Save" class="feedCell-save btn" style="width: 120px;" />
        <input type="button" value="Cancel" class=" btn" onclick="$('#feedCellPopup').trigger('close');" style="width: 120px;" />

控制器

    User userAssignTo = db.Users.FirstOrDefault(p => p.User_Name == assignHar);
            AnimalGroup mob = db.AnimalGroups.FirstOrDefault(p => p.id == mobId);



            db.TaskUsers.Add(new TaskUser()
            {
                userId = userAssignTo.User_ID,

                taskId = taskX.id,
            });
            db.SaveChanges();

            //get user which is logged in.
            string username = System.Web.Security.Membership.GetUser().UserName;
            User user = db.Users.FirstOrDefault(p => p.User_Name == username);